Wideband Code Division Multiple Access (WCDMA) is a 3rd Generation Partnership Project (3GPP) air-interface standard that generally achieves higher speeds and supports more users than many other wireless communication standards. To better utilize WCDMA resources, particularly during times when uplink interference is favorable, WCMDA may use an Enhanced Uplink (EUL) feature to increase capacity and throughput and to reduce delay.
The effectiveness of EUL largely depends on the effectiveness and/or accuracy of the scheduler used to schedule the uplink traffic. In general, the scheduler is responsible for scheduling EUL traffic to multiple users and enhancing user and cell capacity. At the same time, the scheduler is responsible for keeping track of the air-interface cell load and avoiding over-scheduling, keeping track of other available traffic, e.g., transport resources and hardware, receiving, measuring, and estimating variables relevant to the scheduling operation, and transmitting scheduling orders to the mobile terminals, primarily in the form of granted power/bitrates. The scheduler also needs to operate within the constraints specified by the 3GPP standard, e.g., with respect to limited grant transmission capacity, grant transmission delays, grant step up rate limitations, standard limited UE status information, etc.
Conventional schedulers use various different approaches to schedule EUL traffic. For example, a scheduler may allocate the maximum data rate to all mobile terminals as long as resources are available in an order defined by a priority list. When sufficient resources are not available, the scheduler invokes overload handling, which reduces the priority of the mobile terminals with the best grant. Such scheduling practices experience a dead time until re-scheduling takes effect, which results in a loss of capacity. Another conventional scheduler may implement EUL scheduling based solely on a current air-interface load. While the current air-interface load is a useful scheduling tool, it does not account for errors that may occur when estimating the current air-interface load. Such estimation errors reduce the efficiency and increase the losses associated with these schedulers.
Overall, conventional schedulers do not properly account for previous scheduling decisions, delays, and/or exact timing associated with the scheduling process. Further, conventional scheduling algorithms do not fully or directly account for a measured air-interface load. Thus, there remains a need for improved EUL scheduling.